Add missing MMX PSUBQ.

llvm-svn: 43488
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 27685a8..ab24083 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -498,6 +498,7 @@
     setOperationAction(ISD::SUB,                MVT::v8i8,  Legal);
     setOperationAction(ISD::SUB,                MVT::v4i16, Legal);
     setOperationAction(ISD::SUB,                MVT::v2i32, Legal);
+    setOperationAction(ISD::SUB,                MVT::v1i64, Legal);
 
     setOperationAction(ISD::MULHS,              MVT::v4i16, Legal);
     setOperationAction(ISD::MUL,                MVT::v4i16, Legal);